1. Field of the Invention
The present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition suitable for use in an ultramicrolithography process such as production of VLSI or a high-capacity microchip or in other photofabrication processes, and a resist film and a pattern forming method using the composition.
2. Description of the Related Art
In the process of producing a semiconductor device such as IC and LSI, microprocessing by lithography using a photoresist composition has been conventionally performed. Recently, the integration degree of an integrated circuit becomes higher and formation of an ultrafine pattern in the sub-micron or quarter-micron region is required. To cope with this requirement, the exposure wavelength also tends to become shorter, for example, from g line to i line or further to KrF excimer laser light. At present, other than the excimer laser light, development of lithography using an electron beam, an X ray or EUV light is also proceeding.
Above all, the electron beam lithography is positioned as the next or next-next generation pattern formation technique, and a positive resist having high sensitivity and high resolution is demanded. Particularly, in order to shorten the wafer processing time, the elevation of sensitivity is very important, but in a positive resist for electron beam lithography, when higher sensitivity is sought for, not only reduction in the resolution but also worsening of line edge roughness are brought about, and development of a resist satisfying all of these properties at the same time is strongly demanded. The line edge roughness as used herein means that the resist edge at the interface between the pattern and the substrate irregularly fluctuates in the direction perpendicular to the line direction due to the resist properties and when the pattern is viewed from right above, the edge gives an uneven appearance. This unevenness is transferred in an etching step using the resist as a mask and causes deterioration of electric property, giving rise to decrease in the yield. In particular, in an ultrafine region of 0.25 μm or less, the improvement of line edge roughness is a very important problem to be solved. High sensitivity is in a trade-off relationship with high resolution, good pattern profile and good line edge roughness, and it is very important how satisfy all of these requirements at the same time.
Also in the lithography using X-ray or EUV light, it is similarly a very important task to satisfy all of high sensitivity, high resolution, good pattern profile and good line edge roughness at the same time, and this task needs to be solved.
Furthermore, in the case of using a light source that emits EUV light, the wavelength of light belongs to an extreme-ultraviolet region and unlike conventional light sources, high energy of the light brings about a prominent outgassing problem of a compound in the resist film being destroyed by fragmentation to volatize as a low molecular component during exposure and contaminate the environment in the exposure apparatus.
For example, US 2007/0117043 has proposed a technique of bonding a moiety capable of generating an acid upon exposure to an acid-decomposable resin in a resist, where a resist enabling achieving high sensitivity, high contrast, high resolution and/or high dry etching resistance is supposed to be obtained.